The present invention relates to an aircraft engine unit comprising an improved front engine attachment.
As illustrated in FIGS. 1 and 2, an aircraft 10 comprises a plurality of engine units 12 which are positioned below the wing 14 of the aircraft 10 in accordance with a configuration.
As illustrated in FIG. 2, an engine unit 12 comprises an engine 15, a nacelle 16 positioned around the engine 15 and a mast 18 which assures the connection between the engine 15 and the rest of the aircraft 10, in particular the wing 14.
As illustrated in FIGS. 3A and 3B, the mast 18 comprises a rigid primary structure 20 which assures, amongst other things, the transmission of forces between the engine 15 and the rest of the aircraft 10, and a secondary structure 21 which surrounds the primary structure 20 and which limits the drag of the mast.
The present invention is aimed more particularly at aircraft engines of the bypass turbojet type. As illustrated in FIGS. 3A and 3B, this type of engine 15 comprises a core 22 which, in particular, comprises a rotor that pivots relative to a stator about an axis of rotation 24, and a fan casing 26 which has an approximately cylindrical shape and in which there is positioned a fan connected to the rotor of the core 22 of the engine.
Throughout the description, the terms front and rear refer to the direction of the flow of gases, the front corresponding to the intake of gases (air) into the engine and the rear corresponding to the exhaust of gases (combustion gases). In addition, an intermediate part of an element corresponds to a part disposed between a front part and a rear part. The terms top and bottom refer to the connections between the mast and the rest of the aircraft, the top corresponding to the connection between the mast and the wing of the aircraft and the bottom corresponding to the connection between the mast and the engine.
The core 22 extends from a front casing 28 comprising an air intake to a rear casing 30 comprising a combustion gas exhaust.
In accordance with one design, the primary structure 20 of the mast 18 is connected to the engine 15 by a connection which comprises a rear engine attachment 32, a front engine attachment 34, and a pair of thrust rods 36 which assure a take-up of the thrust forces.
In accordance with a first variant illustrated by FIG. 3A and described in document FR-2.963.320, the rear engine attachment 32 connects an intermediate part 38 of the primary structure 20 of the mast 18 and the rear casing 30 of the core 22 of the engine 15, the front engine attachment 34 connects the front end 40 of the primary structure 20 of the mast 18 and the front casing 28 of the core 22 of the engine 15, and the thrust rods 36 connect the intermediate part 38 of the primary structure 20 and the front casing 28 of the core 22 of the engine. In accordance with a first disadvantage associated with this variant, the zone situated between the core 22 of the engine and the primary structure 20 is reduced and does not allow the integration of additional pieces of engine equipment, which are consequently positioned above the primary structure 20 of the mast. This arrangement leads to an increase in the volume of the secondary structure 21 and affects the drag of the aircraft.
In accordance with another disadvantage, this variant results in a relatively significant distance between the core 22 of the engine and the wing 14.
In accordance with a second variant illustrated by FIG. 3B, the front engine attachment 34 connects the front end 40 of the primary structure 20 of the mast 18 and the fan casing 26. This solution increases the zone situated between the core 22 of the engine and the primary structure 20, which makes it possible to house additional pieces of engine equipment there. This variant also results in a reduction of the distance between the core 22 of the engine and the wing 14. However, because the front end 40 of the primary structure 20 is positioned above the fan housing 26, this second variant limits the diameter of the fan housing 26. This diameter is tending to grow more and more due to the rise in the dilution ratio of new engines.